1. Field of the Invention
The invention relates to optical disc drives, and in particular to an optical disc drive with improved playability and a method thereof.
2. Description of the Related Art
Optical discs include read-only types (e.g. CD-DA, CD-ROM, DD-ROM, DVD-Video, DVD-ROM), write-once recordable types (e.g. CD-R, DD-R, DVD-R, DVD+R), and rewritable types (CD-RW, DD-RW, DVD-RW, DVD+RW, DVD-RAM, Blu-ray Disc). An optical disc drive accesses optical discs with a laser beam to either in a continuous spiral or in concentric circles, in which data is prerecorded during the manufacturing process for read-only media or can be written to recordable and rewritable media. In the subsequent descriptions, the expression “playing” a disk will be used for writing as well as for reading (playback).
In optical disc drives, optical pickup heads read track information and servo units accurately follow the track according thereto in three dimensions, radial, focus, and rotational speed. In normal operation, the servo unit obtains information from the optical pickup head and uses it to determine whether the optical pickup head is correctly positioned with respect to the track, and if not, what corrective action is needed. This operation takes place automatically by employing control loops with no need to adjust the servo settings while tracking or focusing with the laser beam.
The optical disk may, however, suffer from mechanical defects such as scratches, fingerprints, dust, dirty areas that obscure data in the disc, which may not only affect decoding of the retrieved data, but also disrupt servo function. Disc playability can be enhanced by assigning specific operating parameters of servo units to all defective area. However, this approach does not optimize the disc playability.
Thus a need exists for an apparatus and method to provide optimal operating parameters to access defective area on optical discs.